Specific purposes of this research are: (a) to establish the importance of peripheral sensory inputs in determining the susceptibility of chemosensitive lateral hypothalamic neurons to several known central influences, (b) to examine the presynaptic connections for involvement of several likely neurotransmitters, such as acetylcholine and norepinephrine, and (c) to establish the functional relations of two lateral hypothalamic efferent pathways. Chemosensitivity will be established in terms of unit electrical activity changes during the intravenous administration of various substances and more directly by the microiontophoretic application of the same substances in the vicinity of the cell by utilizing seven barrel capillary microelectrodes. Interactions with various peripheral stimuli, such as stomach distention and changes in gut contents, will be determined along with electrical stimulation of the lateral preoptic region and several other known central influences. Results will be important in understanding how oral and gastrointestinal factors control ingestive behavior. Specific items of permanent equipment are requested in this supplement proposal in order to increase the capabilities of our current computerized data collection system and thereby improve the quality and production of information in the presently funded research project.